Michell Instruments
latest Ceramic Moisture Sensor has been designed using a 360°
development process which looked at the needs of all potential
stakeholders in the product; from the technical requirements
of the customer, through ease of manufacturing and service, to
the look and feel of the instrument to the user.

Operation of
the sensor depends upon the adsorption of watervapour into a
porous non-conducting "sandwich" between two conductive
layers built on top of a base ceramic substrate. The active sensor
ayer is very thin - less than one micron (a millionth of a metre)
and the porous top conductor that allows transmission of water
vapour into the sensor is less than 0.1 micron thick.

Therefore the
sensor responds very rapidly to changes in applied moisture,
both when being dried (on process start-up) and when called into
action if there is moisture ingress into a process.

Despite this
extreme sensitivity to changes in moisture content, the Michell
Ceramic Moisture Sensor is incredibly rugged due to the nature
of its construction. To protect the sensor further against contaminants
and large particulates it is housed in a protective sintered
stainless steel guard.

Michells
Ceramic Moisture Sensor has been proven time and again in virtually
every application, from pure gases to corrosive processes. The
sensor can withstand the most aggressively acid media - for example
virtually 100 % hydrogen sulphide - conditions in which no other
humidity sensor will survive. If oil, other liquids or solid
matter contaminates the sensor, it can be safely cleaned using
distilled water, high purity solvent such as acetone, or a combination
of the two. This cleaning process will not damage the sensor
or affect its calibration accuracy, provided our recommended
procedures are observed.

The Ceramic Moisture
Sensor handles not only high gas pressures, but also rapid changes
in pressure, without damage. Some less robust dew-point sensors
will be damaged by rapid pressurisation/ de-pressurisation due
to the inferior method of construction. The Ceramic Moisture
Sensor is constructed in such a way that virtually instantaneous
pressurisation right up to the 30 MPa (300 bar) limit will not
cause failure.

All Ceramic Moisture
Sensors are calibrated over the full dew point range from -100
to +20 °C dew point using state-of-the-art computer controlled
humidity generators with mass flow controller operation. Each
sensor is individually calibrated at 10 °C dew point intervals
with the exact calibration data stored in an on-board

processor memory.
This ensures both the optimum calibration accuracy and makes
re-certification very easy to perform, allowing you to maintain
conformance with your own quality assurance requirements.
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